I never got around to ask this question. Most of you have noticed that ID, AI and PS give different full colour translations of a Pantone colour. And then there's Pantone who says something completely different on their colour fans. Now who's right, and for CS which of the 3 is the most accurate? I'm working with CS 5.5 Master, my Pantone colour fans are 4th Edition, 2nd printing.

ID, AI and PS give different full colour translations of a Pantone colour

If you are looking at solid ink libraries then you have to compare the Lab values, which do match between the three programs as long as you are comparing the same libraries.

If you are converting the Lab swatch values to CMYK or RGB the results depend on the document's profile, or the current working color spaces if there's no document profile.

So if you look at Photoshop's Color Picker and pick Pantone Purple, you get different CMYK or RGB values depending on the current Color Setting's Working Spaces and conversion options. Below is US SWOP Coated/AdobeRGB vs. Japan Coated/sRGB—note the Lab values don't change and are the same values you would get in ID or AI.

US SWOP Coated CMYK, AdobeRGB

Japan Coated CMYK, sRGB

Pantone has recommended CMYK translations, but the values would have to be for one particular set of printing conditions. No translation would work for Pantone Purple because that color is out of the CMYK gamut.

Thanks Rob. The question was: why do I get 3 different cmyk values under the same colorspace (Europe, prepress 3) from PS, AI and ID for the same Pantone colour? And: which app gives the right/best values of the 3? I don't move colours between the 3, I just want to know which of the 3 delivers the right translation and why do the Pantone fans give different values than PS, AI and ID? Thanks!

Thanks Rob. The question was: why do I get 3 different cmyk values under the same colorspace (Europe, prepress 3) from PS, AI and ID for the same Pantone colour?

I'm not seeing that with the Pantone + Solid Libraries when the solid spot colors are Lab.

Make sure InDesign and Illustrator are set to define spots as Lab (in Photoshop solid libraries are always Lab). In ID it's under Ink Manager. In AI it's Spot Colors... under the Swatches flyout.

Also make sure the document CMYK assignments (Edit>Assign Profiles) are Europe Prepress 3 before you convert the swatch to CMYK. It's the assigned color profile not Color Setting's Working CMYK profile that makes the conversion, so simply syncing your color settings might not work.

Pantone can't print conversions for every printing condition on their swatches so their CMYK values are somewhat arbitrary—they would have to be for one specific condition.

If you don't want color managed conversions use the Pantone + Color Bridge libraries, which are set CMYK builds.

Here's what I get for Pantone Cool Gray 10 solid conversions in the 3 apps when US Sheetfed is the assignment:

Thanks Rob. I'm working under CS5.5 but CS6 will arrive here this week. I'm used to work either in spot colours or cmyk. Most of the time the logo's used in the projects are either cmyk or Pantone. I always learned that the cmyk percentages must be integers, not decimals. But that descends from the Xpress days and I don't know if plate makers can handle decimals nowadays. At least Pantone uses integers.

I haven't seen fractional percentages cause a problem (and I suspect that may RIPs just round or truncate them). Holding color to +/- 1% on press for any plate would be well within the normal variation of a press run anyway and it's pretty unlikely that you'd see a significant difference between 10% and 10.05%, for example, and probably not even for a difference between 10% and 11%.

I always learned that the cmyk percentages must be integers, not decimals

The output would have to be real numbers if the device is capable of outputting 8-bits per channel (256 not 100 levels of gray). I don't know why ID let's you choose percentages and PS doesn't

I just found the differences between Pantone and Adobe pretty remarkable

Adobe isn't providing a CMYK formula, you're getting a color managed conversion from a Lab color to CMYK. It's the same as when you convert an RGB color to CMYK, the resulting CMYK values could be anything depending on the source RGB and destination CMYK profiles.

You can see the problem with CMYK definitions with a spot color like Pantone 253—it can't be accurately printed or displayed with CMYK values. But if you prefer to have an unchanging set of CMYK values you can use the Pantone + Bridge library.